As cationic surface sizing agents, quaternary cationic copolymers obtained by copolymerizing styrenes and tertiary amino group-containing monomers and emulsions obtained by polymerization of hydrophobic monomers in the presence of the cationic copolymers have been known so far. Specific examples thereof are as follows.
(1) Patent Document 1
As an object of improving sizing effect, a surface sizing agent obtained by mixing cationic hydrophobic polymers obtained by polymerization reaction of (a) 90 to 60% by mole of styrenes, (b) 0 to 30% by mole of tertiary or quaternary amino-containing monomers, and (c) 0 to 10% by mole of other vinyl monomers (such as (meth)acrylic esters, vinyl acetate, acrylonitrile, acrylamides, (meth)acrylic acid) in an organic solvent with cationized starch are disclosed (reference to claims 1 to 6, paragraphs 6 to 7).
(2) Patent Document 2
As an object of imparting a good sizing property and dissociation property to a manufactured paper, disclosed is a cationic polymer emulsion, which is usable as an internal sizing agent or a surface sizing agent, obtained by adding copolymers to water wherein the copolymers are composed of constituent monomers including (1) 50 to 98.5% by mole of styrenes, (2) 0.1 to 9.9% by mole of dialkylaminoalkyl(meth)acrylic esters or a salt thereof, (3) 0.1 to 10% by mole of quaternized compounds of (2), and (4) 0 to 48.5% by mole of (meth)acrylic acid alkyl esters and having the total amount of (2) and (3) of 1.5 to 10% by mole, and obtained by solution polymerization or bulk polymerization (reference to CLAIMS, pages 2 to 3).
(3) Patent Document 3
As an object of decreasing crud generation at the time of polymerization, improving the sizing efficiency and ink-jet printability, and decreasing the foaming property or the like, a cationic surface sizing agent containing (A) cationic copolymers obtained by quaternizing copolymers of hydrophobic monomers and tertiary amino group-containing monomers with oxides, or a cationic surface sizing agent containing copolymers obtained by polymerization (particularly emulsion polymerization: paragraph 25) of (B) hydrophobic monomers such as styrenes and (meth)acrylic esters in the presence of the cationic copolymers (A) are disclosed (reference to claims 1 to 6).
(4) Patent Document 4
As an object of decreasing crud generation at the time of polymerization, improving the sizing efficiency and ink-jet printability, and decreasing the foaming property or the like, disclosed is a cationic surface sizing agent containing copolymers obtained by polymerization (particularly emulsion polymerization: paragraph 29) of (B) hydrophobic monomers such as styrenes and (meth)acrylic esters in the presence of mixtures of cationic copolymers (A-1) obtained by quaternizing copolymers of hydrophobic monomers and tertiary amino group-containing monomers and nonionic surfactants (A-2) (reference to claims 1 to 3).
(5) Patent Document 5
As an object of improving the sizing effect, a surface sizing agent obtained by emulsion polymerization of (C) hydrophobic monomers such as styrenes and (meth)acrylic esters using (B) cationic copolymers obtained by quaternizing (A) copolymers of (a) styrenes and (b) dialkylaminoalkyl(meth)acrylamides as an emulsion dispersant is disclosed.
(6) Patent Document 6
In the above Patent Document 5, those obtained by using (b) dialkylaminoalkyl (meth)acrylates in place of (b) dialkylaminoalkyl(meth)acrylamides in a former clause and monomer mixtures of styrenes and (meth)acrylic ester monomers as the hydrophobic monomers (C) in a latter clause are disclosed.
(7) Patent Document 7
It is disclosed that a sizing agent containing water-soluble or water-dispersive copolymers of styrenes, dialkylaminoalkyl(meth)acrylates and/or dialkylaminoalkyl (meth)acrylamides as constituent monomers is used for transfer paper for electrophotograph containing calcium carbonate as a filler (reference to CLAIMS). In this case, the rate of used styrenes is 40 to 95% by mole (reference to upper right column of page 3).
(8) Patent Document 8
As an object of improving the antirust property and sizing property, a surface sizing agent containing quaternized copolymers composed of 50 to 95% by mole of styrenes and 5 to 50% by mole of dialkylaminoalkyl(meth)acrylamides is disclosed (reference to CLAIMS).
(9) Patent Document 9
Disclosed is a cationic surface sizing agent containing terpolymers in form of an aqueous solution that are composed of 8 to 20% by weight of dimethylaminoethyl (meth)acrylate (a), 45 to 80% by weight of styrene (b), and 8 to 35% by weight of acrylonitrile (c) (preferably 8 to 20% by weight of the component (a), 55 to 75% by weight of the component (b), and 10 to 30% by weight of the component (c)) and are having at least 10% of quaternized dimethylamino groups (reference to claims 1 and 2 in CLAIMS).    Patent Document 1: Japanese Unexamined Patent Publication No. 11-323774    Patent Document 2: Japanese Unexamined Patent Publication No. 4-34097    Patent Document 3: Japanese Unexamined Patent Publication No. 2001-295197    Patent Document 4: Japanese Unexamined Patent Publication No. 2001-262495    Patent Document 5: Japanese Unexamined Patent Publication No. 11-279983    Patent Document 6: Japanese Unexamined Patent Publication No. 11-256496    Patent Document 7: Japanese Unexamined Patent Publication No. 3-167397    Patent Document 8: Japanese Unexamined Patent Publication No. 2-26997    Patent Document 9: Japanese Unexamined Patent Publication No. 56-118994